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General Theory and Calculations Flashcards

7 cards from real PC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 General Theory and Calculations flashcards as text

  1. A 120V, 60Hz circuit has an inductor with 10Ω inductive reactance. What is the inductance (L) in millihenries?

    Answer: 26.5 mH

    XL = 2πfL → L = XL / (2πf) = 10 / (2π × 60) ≈ 26.5 mH.

  2. When two 100 µF capacitors are connected in series, what is the total capacitance?

    Answer: 50 µF

    For equal capacitors in series, C_T = C/n = 100/2 = 50 µF.

  3. A 480V, 3-phase balanced load consumes 50 kW at 0.8 PF lagging. What is the line current?

    Answer: 75.1 A

    I = P / (√3 × VL × PF) = 50,000 / (1.732 × 480 × 0.8) ≈ 75.1 A.

  4. What is the capacitive reactance of a 100 µF capacitor at 60 Hz?

    Answer: 26.5 Ω

    XC = 1 / (2πfC) = 1 / (2π × 60 × 0.0001) ≈ 26.5 Ω.

  5. In a 3-phase wye (Y) system, how does line voltage relate to phase voltage?

    Answer: V_line = V_phase × √3

    In a wye system, line voltage is √3 (≈1.732) times the phase voltage.

  6. A circuit has 8Ω resistance and 6Ω inductive reactance in series. What is the impedance?

    Answer: 10 Ω

    Z = √(R² + XL²) = √(64 + 36) = √100 = 10 Ω.

  7. What is the unit of electrical conductance, and how does it relate to resistance?

    Answer: Siemens; G = 1/R

    Conductance (G) is measured in Siemens and is the reciprocal of resistance: G = 1/R.